1. Field of the Invention
The present invention relates to an image display device and an image display apparatus that display an image by a pixel group formed by a plurality of pixels.
2. Description of the Related Art
Projection type video display devices, for example, that display a picture using a plurality of image display devices employ a system referred to as a three-panel type system using three image display devices. This method separates light into three colors of red, green, and blue, changes the luminance of each of the colors by the image display devices, and thereafter synthesizes the results by an optical block such as a prism, whereby a desired picture is obtained.
Because an image display device is provided for each of the colors of red, green, and blue, this method has advantages of excellent color reproducibility and high brightness. On the other hand, the method has disadvantages in that circuitry is complex because three display devices may be required and registration of the display devices for the respective colors may be required.
The registration of the image display devices is necessary to display an image formed in red, an image formed in green, and an image displayed in blue such that the image formed in red, the image formed in green, and the image displayed in blue are superimposed on each other. The image display devices need to be registered with each other precisely with an accuracy of about one pixel. When the registration is not performed with high precision, a picture with a color shift is displayed, and therefore it is difficult to achieve high-quality picture display.
One pixel in an image display device is very small, and can be as small as a few μm. It is therefore very difficult to register the image display devices. Since the pixel size of liquid crystal display devices used in a projection type liquid crystal display device tends to be decreased, it is considered that the registration will become increasingly difficult in the future. Furthermore, even when the precision at the time of attachment is high, the attachment position can be slightly shifted with the passage of time.
As described above, the registration of devices may require a precision with which the devices are bonded to an optical block such as a prism within a displacement of one pixel and an attachment structure that prevents a secular change in the attachment position of the display devices. Japanese Patent Laid-Open No. Hei 8-184928 discloses a structure for registering image display devices in a projection type video display device in the past.